Energy transfer within self-assembled cyclic multichromophoric arrays based on orthogonally arranged donor–acceptor building blocks

Abstract

We herein present the coordination-driven supramolecular synthesis and photophysics of a [4+4] and a [2+2] assembly, built up by alternately collocated donor-acceptor chromophoric building blocks based, respectively, on the boron dipyrromethane (Bodipy) and perylene bisimide dye (PBI). In these multichromophoric scaffolds, the intensely absorbing/emitting dipoles of the Bodipy subunit are, by construction, cyclically arranged at the corners and aligned perpendicular to the plane formed by the closed polygonal chain comprising the PBI units. Steady-state and fs time-resolved spectroscopy reveal the presence of efficient energy transfer from the vertices (Bodipys) to the edges (PBIs) of the polygons. Fast excitation energy hopping - leading to a rapid excited state equilibrium among the low energy perylene-bisimide chromophores - is revealed by fluorescence anisotropy decays. The dynamics of electronic excitation energy hopping between the PBI subunits was approximated on the basis of a theoretical model within the framework of Förster energy transfer theory. All energy-transfer processes are quantitatively describable with Förster theory. The influence of structural deformations and orientational fluctuations of the dipoles in certain kinetic schemes is discussed.

Towards Efficient Spectral Converters through Materials Design for Luminescent Solar Devices

“…[51] There have been several reports of dendritic structures that exhibit a Stokes' shift that is large enough to reduce reabsorption. [52][53][54][55][56] For example, Akkaya et al reported a dendritic system composed of borondipyrromethene (bodipy) dyes with varying degrees of functionalization with styryl groups.…”

The effect of protonation on the excited state dynamics of pyrimidine chromophores

“…Initially, a femtosecond time resolved upconversion (FU) system, described in details in the past has been used. 65,66 The FU system is based on a Ti:Sapphire femtosecond laser (80 fs pulse duration, 80 MHz repetition frequency, 800 nm) which, after passing through a Second Harmonic Generator (SHG) crystal, is frequency doubled at 400 nm and is used for the excitation of the samples. The excitation power was below J o u r n a l P r e -p r o o f 2 mW while the samples were continuously rotating to avoid thermal effects.…”

Photophysical and Protonation Time Resolved Studies of Donor–Acceptor Branched Systems With Pyridine Acceptors

“…For the fs-ps timescale, a femtosecond time resolved upconversion (FU) system has been used using a Ti:Sapphire femtosecond laser (80 fs pulse duration, 80 MHz repetition frequency). 44,45 The second harmonic at 385 nm has been used as the excitation source (less than 1.8 pJ/pulse).…”